Collapsing is when a variable is reported across fewer
categories so that there are fewer cells to populate so there is an increased
chance of getting (albeit less granular) data returned. For example, the
uncollapsed variable Means of Transportation has 18 categories. There are
4 collapsed versions of the variable, where such categories as number in
carpool become less refined (2 or more, as opposed to 2, 3, 4, 5 or more each
as their own category) alternatives to driving may collapse as well, collapsing
is grouping – rather than a category for biking and one for walking, they
are grouped into biked, walked, to capture more cases.
In a variable like income or age, the range would be larger in a
collapsed category, all the cases are allocated to fewer categories so that
each cell may have more cases, so data will have less chance of suppression (not
meeting the minimum cell requirements imposed by the census bureau).
I hope this helps, and does not further confuse.
Penelope
Weinberger
CTPP
Program Manager
AASHTO
202-624-3556
http://ctpp.transportation.org/Pages/default.aspx
It's just as bad to not make a plan as to blindly follow the one
you already have.
From:
ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On
Behalf Of Michael Moan
Sent: Monday, November 22, 2010 10:43 AM
To: ctpp-news@chrispy.net
Subject: [CTPP] RE: [CPP] While you are waiting for the CPP full
datarelease.......
Could some please
explain "collapsing" again and the affect it will have on Cpp and
modeling?
Michael C. Moan,
Principal Planner
Office of Statewide Planning
Division of Planning
Department of Administration
One Capitol Hill
Providence, RI 02908
4012221236
>>> "Weinberger, Penelope" <pweinberger@aashto.org>
11/22/2010 9:32 AM >>>
To see the list of tables that constitute the CTPP 3-year special
tabulation based on 2006 - 2008 ACS go to
http://ctpp.transportation.org/Pages/ACSData.aspx
and click on the "Link
to the list of tables" under the three year data heading. That will
return the spreadsheet of part one (residence based), two (workplace
based) and three (flow) tables, with geography.
What will be released is those tables together with a data access tool,
currently under development (Beta testing now), to access the data for
analysis.
Penelope Weinberger
CTPP Program Manager
AASHTO
202-624-3556
http://ctpp.transportation.org/Pages/default.aspx
It's just as bad to not make a plan as to blindly follow the one you
already have.
-----Original Message-----
From: ctpp-news-bounces@chrispy.net
[mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Garth Banninga
Sent: Friday, November 19, 2010 4:13 PM
To: ctpp-news@chrispy.net
Subject: Re: [CTPP] While you are waiting for the CTPP full data
release.......
Liang:
Exactly what data will be included in the December CTPP release?
CTPP2000 and ACS 2007-2009? or some other periods? I'd appreciate any
clarifications or references you can provide.
Thanks,
Garth Banninga, Planner
MDOT-Planning
Statewide Model Unit
425 W. Ottawa St.
Lansing, MI 48933
517.335.2959
>>> <Liang.Long@dot.gov> 11/19/2010 2:49PM >>>
While you are still waiting for the CTPP full data release with the
access software (scheduled on December, 2010), don't forget FHWA
prepared and released the county-to-county and place-to-place flow
tables prior to full data's formal release. The flow tables are for
Total Workers and for 18 categories of Workers by Means of
Transportation. County level data also included CTPP 2000 data but
categorized only by 8 transportation modes. We have NOT included the
CTPP2000 for Place-to-Place data files because of difficulties in
matching FIPS codes for Places between 2000 and the current CTPP. These
two files are published in CS FTP sites:
ftp://ftp.camsys.com/temp/outgoing/CTPP/New%20CTPP%20ACS/
Also, transportation profiles using ACS 2005-2007 and CTPP2000, which
give people a quick transportation snapshot of their areas are also
published at AASHTO CTPP website.
http://download.ctpp.transportation.org/profiles_2005-2007/ctpp_profiles
.html
Liang Long
Federal Highway Administration
Room 74-440
1200 New Jersey, SE
Washington, DC 20590
tel 202 366 6971
fax 202 493 2198
e-mail liang.long@dot.gov <mailto:liang.long@dot.gov>
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